Threat Description

Die_Hard

Details

Summary

Die_Hard is a resident fast infector which targets COM and EXE files. It is known
to be in the wild especially in India, where it was found in September 1994. Die_Hard
has also been sighted in Singapore, Indonesia, USA and in many parts of Europe.

When the virus is executed, it goes resident in memory, decreasing the available DOS
memory by 9232 bytes. Die_Hard infects all executed or opened COM and EXE files. The
infected files grow by exactly 4000 bytes.

Die_Hard hides beneath several layers of encryption. When the virus is decrypted,
the following texts can be seen:

SW DIE HARD 2 SW Error

Since the virus does not utilize polymorphic encryption techniques, it is quite easy
to find.

Die_Hard activates on the 3rd, 11th, 15th, or 28th of any month, provided the day
is Tuesday and the virus has already infected at least 13 files. The virus will then
wait until some program changes the screen to graphics mode. At this time the virus
will display an animation of large 'S' and 'W' characters on the screen. It will also
deny write access to files, displaying text 'SW Error'.

Besides infecting COM and EXE files, Die_Hard trojanizes ASM and PAS source files
when they are accessed; in other words, the virus inserts source code Trojan horses
in these files.

Removal

Automatic action

Once detected, the F-Secure security product will automatically disinfect the suspect file by either deleting it or renaming it.

More

Detailed instructions for F-Secure security products are available in the documentation found in the Downloads section of our Home - Global site.

You may also refer to the Knowledge Base on the F-Secure Community site for further assistance.

Description Details: Mikko Hypponen, F-Secure

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